FR2773160A1 - COPOLYMER RESIN, ITS PREPARATION AND PHOTORESIST USING THE SAME - Google Patents

Abstract

Disclosed are a copolymer resin, its preparation, and a photoresist using the same. According to the invention, the copolymer resin is characterized in that it has a molecular weight of 3,000 to 100,000, and in that it has a molecular weight of 3,000 to 100,000. that it comprises a mono-methyl cis-5-norbornene-endo-2, 3-dicarboxylate monomer and in that it is represented by formula III where R represents a tert-butyl, hydropyranyl, hydrofuranyl or ethoxylethyl group, and the ratio x: y: z is (0.1 to 99%): (0.1 to 99%): (0.1 to 99%). The invention finds application in the field of the electronics industry.

Description

i 2773160 The present invention generally relates to a resin of

  copolymer for a photoresist used in the manufacture of electronic devices. The photoresist can be used with ultraviolet radiation such as KrF or ArF. More particularly, the present invention relates to processes for the preparation of the photoresist, to processes using the photoresist, and to the photoresist itself. In an exemplary embodiment, the invention relates to a

  photoresist resin, o a mono-methyl cis-5- unit

  norbornene-endo-2,3-dicarboxylate was introduced into a copolymeric structure of norbornene-maleic anhydride for a photoresist, usable in a lithography process using a light source KrF (248 nm) or ArF (193 nm) which could be applied in the DRAM 1G or 4G device, and others; a process for its preparation; and to a photoresist containing

said resin.

  Various types of photoresists have been used or proposed. These photoresists often have a variety of characteristics or properties such as resistance to etching, adhesiveness, and the like. In general, etching resistance, adhesiveness with low light absorption at 193 nm wavelength is desirable for a copolymer resin for ArF. The copolymer resin must also be developable using a 2.38 wt% aqueous solution of tetramethylammonium hydroxide. It is difficult to synthesize a copolymer resin, however satisfying one or more of these properties. Much research has been focused on studies of a Norbolaque type resin as a resin to increase transparency at a wavelength of 193 nm and increase resistance to etching. As an example, Bell Laboratories have attempted to introduce an alicyclic unit into the skeleton chain in order to increase resistance to

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  engraving. The copolymer resin in which the backbone chain has a norborane, acrylate and maleic anhydride substituent is, for example, represented by the chemical formula I:

[FORM I]

+

A OOH

  v 90 1 = o C = O u / C = O 0 The copolymer resin of formula I, in which the anhydrous maleic portion (portion A) used to polymerize an alicyclic olefin group, however, is the only material to polymerize with norbornene, the alicyclic unit, without absorbing the

  ArF light and having a wavelength of 193 nm.

  As a result, it cannot generally be used as a resin for ArF, because it is completely soluble in a 2.38% aqueous TMAH solution. Solubility occurs even without exposure to create a phenomenon of "top loss" (the top of the pattern being formed into a round shape) which is generally seen in the patterning of a conventional photoresist. Thus, in order to prevent such a phenomenon, a portion therein having a tert-butyl substitute must be increased. A relative decrease in the z portion, which increases the sensitivity and tackiness with the substrate causes disadvantages in that the photoresist is removed from the wafer in conventional patterning so that the pattern cannot be formed effectively. Other resist products have been proposed, but these resist products may have

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  many limitations such as difficulty in

  manufacturing, aggressive odors, and the like.

  From the above, it can be seen that a photoresist having better adhesiveness and improved resolution is desired. According to the present invention, the present inventors have developed a copolymer resin of the maleic anhydride type comprising a -norbornene-2-carboxylic acid monomer represented by the chemical formula II as the main constituent, and deposited

  a patent application (Korean patent application No. 97-

  26807 filed June 21, 1997), as an attempt to resolve the limitations of conventional photoresist products. C = O

I

  OH Although a photoresist using the maleic anhydride type copolymer resin suggested by the above application is a polymer resin with high tack, high sensitivity and excellent resolution, there is a problem in manufacturing in practical, because one of the main constituents, 5norbornene-2-carboxylic acid can generate a very aggressive odor during the synthesis process. Thus, the present inventors have developed a new photoresist having an excellent resolution

  without causing an aggressive odor problem.

  In a specific embodiment, the present invention provides a technique for limiting the aggressive odor caused by the resist products.

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  conventional. More particularly, the present invention provides a method of introducing a mono-methyl cis-5norbornene-endo-2,3-dicarboxylate unit in place of 5-norbornene-2carboxylic acid into the structure of the norbornene- copolymer. maleic anhydride. This method solves, in part, all the problems of emitting an aggressive odor. In a preferred embodiment, the present method provides a resulting resist without substantially deteriorating the sensitivity of the resist. The present photoresist also has characteristics such as excellent adhesiveness and resolution (0.13 min). The present resist can be obtained with ease of control of the composition of the constituents during the synthesis of the photoresist resin to make mass production possible. Many advantages or benefits are achieved by the present invention over conventional techniques. In a specific embodiment, the present invention provides a resin for

  copolymer comprising a mono-methyl cis-5- unit

  norbornene-endo-2,3-dicarboxylate. In another embodiment, the present invention provides a process for preparing the copolymer resin comprising the unit

  mono-methyl cis-5-norbornene-endo-2,3-dicarboxylate.

  In yet another embodiment, the present invention provides a photoresist comprising the above norbornene-maleic anhydride copolymer resin, an organic solvent and photoacid generator. Still further, the present invention provides a semiconductor element fabricated using

  the photoresist comprising the above copolymer resin

  above. These and other advantages are described

  in the description and more particularly below.

  The present invention relates to a copolymer resin for a photoresist comprising a unit

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  mono-methyl cis-5-norbornene-endo-2,3-dicarboxylate, which is represented by the chemical formula III [FORMULA IIIj

0 0 0

C = O O = oC C = O C = O o I CH3

R CH2

CH2

0 OH

  where R represents a tert-butyl group, tetra-

  hydropyranyl, tetrahydrofuranyl or ethoxyethyl, and the ratio x: y: z: is (0.1 to 99%): (0.1 to 99%)

: (0.1 to 99%).

  The copolymer resins according to an embodiment of the present invention include

  preferably norbornene copolymer resins

  maleic anhydride represented by the formulas

chemicals IV to VII.

[FORM IV]

CO O OH

+ fCH2

O = C C = O

0 1

U30

CH2

OH

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[FORM V]

(/ 0 ^ X / 0jY / \ / \

0 C = 0 O O0

C = O O = C C = O

ICH2 o QuJ CH2 UH3 OH

[FORM VI]

CO O OH

0 0 O

COC = O O = C C = O

C CH3

OC Cl H2 OH

[FORMULA VII]

0

C = O

C = O O = C C = O

C = O I

È O OH

CH3-CH CH2 CH3

1H2

O-C2H5 H2

OH

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  In the formulas, R, x, y and z are such that

defined above.

  The copolymer resin of the present invention, represented by formula III can be prepared by polymerization of the norbornene derivative of formula VIII, of 2-hydroxyethyl-5-norbornene-2-carboxylate of formula

  IX, maleic anhydride of formula X and mono-methyl-

  cis-5-norbornene-endo-2,3-dicarboxylate of formula XI in

  presence of a radical initiator.

[FORM VIII]

9

C = O R

[FORM IX]

C = O O CH2 CH2

OH

[FORMULA X:

  0

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[FORMULA XI]

O = C C = O

I I O OH CH3

  In the above formulas, R represents a tert-

  butyl, a 2-tetrahydropyranyl, a 2-tetrahydrofuranyl

  or ethoxyethyl or the like.

  In the preparation of the copolymer resin according to the present invention, the norbornene derivatives of chemical formula VIII are preferably selected

  in the group consisting of tert-butyl 5-norbornene-

  2-carboxylate, 2-tetrahydropyranyl-5-norbornene-2-

  carboxylate, 2-tetrahydrofuranyl 5-norbornene-2-

  carboxylate and 2-ethoxyethyl 5-norbornene-2-

  carboxylate. The copolymer resins according to the present invention can be prepared by a conventional polymerization process such as bulk polymerization or solution polymerization. As the solvent, cyclohexanone, methyl ethyl ketone, benzene, toluene, dioxane and / or dimethylformamide can be used individually, or as a mixture. The polymerization initiators which can be used in the present invention include benzoyl peroxide, tert-butyl peracetate,

  di-tert-butyl peroxide, or the like.

  In the process for preparing the copolymer resin according to the present invention, the general polymerization condition including the temperature and the pressure of the polymerization of the radical can be controlled according to the properties of the reactants, but it is

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  better to carry out the reaction of

  polymerization at a temperature between 60 and 200 C.

  The copolymer resin according to the present invention can be used in the formation of a positive micro-image by preparing a photoresist solution in which the resin is mixed with an organic solvent and a conventional photoacid generator according to a conventional method to prepare a photoresist composition. In the process

  to form a photoresist pattern of a semi-element

  conductive, the amount of the copolymer resin according to the present invention depends on the organic solvent or the photoacid generator used, and the condition of the lithography, but conventionally it is approximately 10 to 30% by weight based on the solvent

  organic used in the preparation of the photoresist.

  The process for forming a photoresist pattern of a semiconductor device using the copolymer resin according to the present invention is described in detail below: The copolymer resin according to the present invention is dissolved in cyclohexanone & a concentration of 10 at 30% by weight. A photoacid generator (0.1 to 10% by weight), such as triphenylsulfonium triplate, dibutylnaphthylsulfonium triplate, 2,6-dimethylphenylsulfonate, bis (arylsulfonyl) -diazomethane, oxime sulfonate or 2,1- diazonphatoquinone-4-sulfonate, is incorporated into the photoresist resin. The mixture is then filtered through an ultramicronic filter to prepare a photoresist solution. The photoresist solution is then coated by centrifugation on a silicon wafer to form a thin film, which is then softened by annealing in an oven at 80 to 150 C or on a hot plate for 1 to 5 minutes, exposed to light in using a distant ultraviolet exposure device or an exposure device to a

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  excimer laser, and baked at a temperature between 100 C and C for 10 seconds to 60 minutes. The exposed wafer is impregnated in a 2.38% aqueous TMAH solution for 1 to 30 seconds to obtain a positive photoresist pattern. A better understanding of the present invention will be obtained in the light of the following examples which are given to illustrate, but are not

  not to be considered as limiting, the present invention.

PREPARATION EXAMPLE I

  Synthesis of tert-butyl 5-norbornene-2-carboxylate [FORMULA VIIIa]

C = O

  In Cyclopentadiene (66 g) and a tetrahydrofuran solvent (500 g) were charged to a reactor, and the mixture was stirred homogeneously. To the reaction mixture, tert-butyl acrylate (128 g) was added, and the resulting mixture was stirred at a temperature between -30 C and 60 C for about 10 hours to carry out the reaction. When the reaction was complete, the solvent was removed using a rotary evaporator, and the residue was distilled under reduced pressure to obtain 176 g

  (yield: 90%) of tert-butyl -5-norbornene-2-

  carboxylate represented by the chemical formula VIIIa.

PREPARATION EXAMPLE II

  Synthesis of 2-hydroxyethyl 5-norbornene-2-

  carboxylate (formula IX) The same procedure as that described in Preparation Example I was repeated except that 2-hydroxyethyl acrylate (116 g) was used in place of tert-butyl

  acrylate to give 155 g (yield: 85%) of 2-

  hydroxyethyl 5-norbornene-2-carboxylate represented by

the formula IX described above.

PREPARATION EXAMPLE III

  Synthesis of 2-tetrahydropyranyl 5-norbornene-2-

  carboxylate [FORMULA VIIIb] C = O O 1 = The same procedure as that described in Preparation Example I was repeated except that 2-hydroxyfuranyl acrylate (156 g) was used in place of tert-butyl

  acrylate to give 186 g (yield: 84%) of 2-

  tetrahydropyranyl-5-norbornene-2-carboxylate shown

by formula VIIIb.

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PREPARATION EXAMPLE IV

  Synthesis of 2-tetra-hydrofuranyl 5-norbornene-2-

carboxylate [FORMULA VIIIc] C = O

O

  JCo The same procedure as that described in the Example of

  Preparation I was repeated except that 2-

  tetrahydrofuranyl acrylate (144 g) was used in place of tert-butyl acrylate to give 172 g

  (yield: 82%) of 2-tetrahydrofuranyl norbornene-2-

  carboxylate represented by formula VIIIc.

PREPARATION EXAMPLE V

  Synthesis of 1-ethoxyethyl 5-norbornene -2-

carboxylate [FORMULA VIIId] C = O

CH3 CH

O-C2H5

  The same procedure as that described in Preparation Example I was repeated except that 1-ethoxyethyl

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  acrylate (144 g) was used in place of tert-butyl acrylate to give 174 g (yield: 83%) of ethoxyethyl-5-norbornene-2-carboxylate represented by

formula VIIId.

PREPARATION EXAMPLE VI

  Synthesis of mono-methyl cis-5-norbornene-endo-

  2,3-dicarboxylate (formula XI) In a reactor, cylopentadiene (66 g) was charged, and a solvent tetrahydrofuran (500 g) and maleic anhydride (98 g) were added, and the mixture a was shaken homogeneously. To the reaction mixture, absolute ethanol (500 g) was added and the reaction was carried out with stirring at 50 C for 8 hours. When the reaction was complete, the solvent was removed using a rotary evaporator, the residue was distilled under reduced pressure to obtain 156 g (yield: 87%) of mono-methyl cis-5-norbornene-endo-2,3 -dicarboxylate represented by

the chemical formula XI.

EXAMPLE I

  Synthesis of a poly [ter- copolymer resin

  butyl 5-norbornene-2-carboxylate / 2- hydroxyethyl 5-

  norbornene-2-carboxylate / mono-methyl cis-5-norbornene endo-2,3dicarboxylate / maleic anhydride] (Formula IV) In tetrahydrofuran or toluene were dissolved maleic anhydride (1 mole), tertbutyl - norbornene-2-carboxylate (0.5 - 0.9 mole) prepared

  according to Preparation Example I, 2-hydroxyethyl -5-

  norbornene-2-carboxylate (0.05 - 0.8 mole) prepared according to

  Example II, and mono-methyl cis-5-norbornene-endo-

  2,3-dicarboxylate (0.01 - 0.5 mole) prepared according to

14 2773160

  Preparation Example VI. Then 2,2'-

  azobisisobutyronitrile (AIBN) (0.5 - 10 g) as a polymerization initiator, was added to this, and the reaction was carried out at a temperature between 650C and 700C under a nitrogen or argon atmosphere for 4 to 24 hours. The crude product thus obtained was precipitated from ethyl ether or hexane, and the precipitate was dried to give the title copolymer resin (Formula IV) having a molecular weight of 3,000 to 100,000 (yield: 63 %). The copolymer resin thus prepared has high transparency in the light of ArF, increased etching resistance and excellent adhesiveness, and is developable by a

  2.38% wt TMAH aqueous solution.

EXAMPLE II

  Synthesis of poly [2- copolymer resin

  tetrahydropyranyl 5-norbornene-2-carboxylate / 2-

  hydroxyethyl 5-norbornene-2-carboxylate / mono-methyl cis-5norbornene-endo-2,3dicarboxylate / maleic anhydride] (Formula V) The same procedure as that described in Example I

  was repeated except that 2-tetrahydropyranyl 5-

  norbornene-2-carboxylate prepared according to Preparation Example III was used in place of tert-butyl -norbornene-2-carboxylate, to obtain the title copolymer resin (formula V) having a molecular weight of 3,000 to 100 000 (yield: 68%). Although the protecting group of the copolymer resin thus prepared was substituted with an acetal group, the etching resistance of the resin was not deteriorated, and the resin had excellent

  sensitivity (sensitivity: 11 Nj / cm).

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EXAMPLE III

  Synthesis of poly [2- copolymer resin

  tetrahydrofuranyl 5-norbornene-2-carboxylate / 2-

  hydroxyethyl 5-norbornene-2-carboxylate / mono-methyl cis-5norbornene-endo-2,3-dicarboxylate / maleic anhydride] (Formula VI) The same procedure as that described in Example I

  was repeated except that 2-tetrahydrofuranyl 5-

  norbornene-2-carboxylate prepared according to the Example of

  Preparation IV was used in place of tert-butyl 5-

  norbornene-2-carboxylate, to obtain the title copolymer resin (formula VI) having a molecular weight of 4,000 to 100,000 (yield: 64%). The copolymer resin thus obtained had similar properties

to those of Example II.

EXAMPLE IV

  Synthesis of poly [1- copolymer resin

  ethoxyethyl 5-norbornene-2-carboxylate / 2-hydroxyethyl -norbornene-2carboxylate / mono-methyl cis-5-norbornene-endo-2,3-dicarboxylate / maleic anhydride] (Formula VII) The same procedure as that described in Example I

  was repeated except that 1-ethoxyethyl 5-norbornene-2-

  carboxylate prepared according to Preparation Example 5 a

  been used in place of tert-butyl 5-norbornene-2-

  carboxylate, to obtain the title copolymer resin (formula VII) having a molecular weight of 4,000 to 000 (yield 59%). The copolymer resin thus obtained had properties similar to those of Example I, but had better properties of

contrast point of view.

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EXAMPLE V

  The copolymer resin (Formula IV (0lg) obtained according to Example 1 was dissolved in 3-methoxymethyl propionate (40 g, solvent) and triphenylsulfonium triplate or dibutylnaphthylsulfonium triplate (about 0.2 to 1 g) as photoacid generator was added thereto. After stirring, the mixture was filtered through a 0.10 µm filter to give a photoresist solution. Then the photoresist solution was coated by centrifugation on a surface of slice to prepare a thin film having a thickness of 0.4 to 1.2 μm, and the slice was softened by annealing in an oven of 70 to 150 ° C. or on a hot plate for 1 to 5 minutes. light with a wavelength of 250 nm using an exposure device, it was post-cooked at 90-1600 C. Then the exposed wafer was soaked in an aqueous TMAH solution having a concentration of 0, 01 to 5% by weight as development solution development for 1.5 minutes to obtain an ultra-micron photoresist pattern

(resolution: 0.13 pim).

EXAMPLE VI

  The same procedure as that described in Example V was repeated except for the use of the copolymer resin (formula V) prepared according to Example II as a photoresist resin, to form a pattern of

ultra-micron photoresist.

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EXAMPLE VII

  The same procedure as that described in Example V was repeated except for the use of the copolymer resin (formula VI) prepared according to Example III as a photoresist resin, to form a pattern of

ultra-micron photoresist.

EXAMPLE VIII

  The same procedure as that described in Example V was repeated except for the use of the copolymer resin (formula VII) prepared according to Example IV as a photoresist resin, to form a pattern of

photoresist.

  In case a pattern is formed using the

  photoresist as described above, a semi-element

  conductor with 0.13 fm micro-pattern can be fabricated, so that a highly integrated element can

be advantageously obtained.

  As described above, the copolymer resin for the photoresist of KrF (247 nm) or ArF (173nm) according to the present invention is easily prepared by conventional radical polymerization due to

  of the introduction of the mono-methyl cis-5- unit

  norbornene-endo-2,3-carboxylate in the structure of the polymer. The resin has a high transparency at a wavelength of 193 nm, provides increased etching resistance and solves the problem of an aggressive odor appearing during the synthesis of the copolymer resin. In addition, since the resin composition can be easily controlled due to the molecular structure, the resin can be manufactured on a large scale. Thus, the copolymer resin for KrF or ArF according to the present invention can be used

  usefully in a lithography process.

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  Many modifications and variations of the present invention are possible in light of the

  lessons above. Therefore, it should be understood that within the scope of the appended claims, the invention5 can be practiced other than as specifically described.

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R_EV E ND ICA T I NS

  1. Copolymer resin characterized in that it has a molecular weight of 3,000 to 100,000, and in that it comprises a monomethyl cis-5-norbornene-endo-2,3-dicarboxylate monomer and is represented by the following formula III: Formula III () O) y $ Ä 1u

0O O

0 0 O

C = O O = C C = O

C = O CIO I

c = o b OH o CH3

R CH2

  CH2 I OH o, R represents a tert-butyl, hydropyranyl, hydrofuranyl or ethoxyethyl group, and the ratio x: y: z

  is (0.1 to 99%): (0.1 to 99%): (0.1 to 99%).

  2. Copolymer resin according to claim 1, characterized in that it is a resin of norbornene-maleic anhydride copolymer represented by the following formula IV: formula IV <9 O 4O Sx (0 0

= O C O OH

O CH3

C H2

CH2

OH

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  o, the ratio x: y: z is (0.1 to 99%): (0.1 to

* 99%) (0.1 to 99%)

  3. Copolymer resin according to claim 1, characterized in that it is a resin of norbornene-maleic anhydride copolymer represented by the following formula V: formula V

0 0 O

C = O O = C C = O

cl = o | OO

1O I- CH3

O

  OH o, the ratio x: y: z is (0.1 to 99%): (0.1 to

99%): (0.1 to 99%).

  4. Copolymer resin according to claim 1 characterized in that it is a resin of norbornene-maleic anhydride copolymer represented by the following formula VI: formula VI

0 0 0

C = O O = C C = O

C - == O O OH

 O CH3

I CH2

CH2 OHO

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  o, the ratio x: y: z is (0.1 to 99%): (0.1 to

99%): (0.1 to 99%).

  5. Copolymer resin according to claim 1, characterized in that it is a resin of norbornene-maleic anhydride copolymer represented by the following formula VII: formula VII C10 o OH

C = O OI CH3

CH3- CH2

O- C2H5 CH2

  OH o, the ratio x: y: z is (0.1 to 99%): (0.1 to

99%): (0.1 to 99%).

  6. Method for preparing the copolymer resin of formula III defined in claim 1, characterized in that it comprises the step of polymerization, in the presence of a radical initiator, of the norbornene derivative represented by formula VIII, 2hydroxyethyl-5-norbornene-2-carboxylate represented by formula IX, maleic anhydride represented by

  formula X and mono-methyl-cis-5-norbornene-endo-2,3-

  carboxylate represented by formula XI:

C = O C = O

I = .0 ^^^^ o o0 01 O O = C C = O I I

R 0 OH

  R C | H2 Formula X OH Formula VIII CH2 CH3 OH Formula XI Formula IX

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  o R represents a tert-butyl, a 2-tetrahydropyranyl,

  a 2-tetrahydrofuranyl or an ethoxyethyl.

  7. Method according to claim 6, characterized

  in that the norbornene derivative is tert-butyl 5-

  norbornene-2 carboxylate represented by the following formula VIIIa, [FORMULA VIIIa] C = O I =

O

  8. Method according to claim 6, o the derivative

  of norbornene is 2-tetrahydropyranyl 5-norbornene-2-

  carboxylate represented by formula VIIIb, [FORMULA VIIIb] C = O O t O 9. Process according to claim 6, characterized in that the norbornene derivative of 2-tetrahydrofuranyl - norbornene-2-carboxylate represented by the formula formula VIIIc,

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  FORMULA VIIIc] C = O O O 0 10. Process according to Claim 6, characterized in that the norbornene derivative is 2-ethoxyethyl norbornene-2-carboxylate represented by the formula VIIId, [FORMULA VIIId] C = O O I

CH3 -CH

O-C2H5

  11. A method of preparing the copolymer resin according to claim 6, characterized in that the polymerization initiator is selected from

  the group consisting of benzoyl peroxide, 2,2'-

  azobisisobutyronitrile, acetyl peroxide, lauryl peroxide, tert-butyl peracetate and di-tert-butyl peroxide. 12. Process for preparing the copolymer resin according to claim 6, characterized in that the polymerization is carried out in the presence of a solvent or a mixture of solvents selected from the

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  group consisting of cyclohexanone, methyl ethyl ketone, benzene, toluene, dioxane and dimethylformamide. 13. A method of preparing the copolymer resin according to claim 6, characterized in that the polymerization is carried out at a temperature between 60 C and 200 C under an atomosphere

argon or nitrogen.

  14. Photoresist composition characterized in that

  that it includes a norbornene copolymer resin-

  maleic anhydride defined in any of

  claims 1 to 5, an organic solvent and a

photoacid generator.

  15. A photoresist composition according to claim 14, characterized in that the photoacid generator is triphenethylsulfonium triplate or

dibutylnaphthylsulfonium triplate.

  16. A photoresist composition according to claim 14, characterized in that the copolymer resin is contained in an amount between 10% by weight

  and 30% by weight based on the amount of solvent.

  17. A photoresist composition according to claim 14, characterized in that the photoacid generator is contained in an amount between 0.01% by weight and 10% by weight based on the amount of resin

of copolymer.

  18. Semiconductor device fabricated using the photoresist composition comprising the

  the copolymer resin of claim 14.